This invention relates in general to gas detection devices and in particular to a new and useful mouthpiece construction for a breath alcohol measuring device.
All over the world, there are commercially available breath-alcohol measuring devices into which breath is to be blown by a person being tested. For this purpose, such devices are equipped with a mouthpiece which must comply with certain requirements. They must be hygienically handled, and preferably exchangeable after use, thus disposable. Consequently, they must be inexpensive in manufacture.
A prior art mouthpiece for breath testing apparatus comprises a set of two members, namely a cup and a connection piece. The connection piece is passed through the bottom of the cup. In the interior of the cup, the connection piece terminates by a closed end and radial apertures. The complete mouthpiece is to be connected to the breath measuring device by the outer end of the connection piece. During the breath test, the mouthpiece is pressed around the mouth against the face so that the rim of the cup sealingly surrounds the lips. The connection piece end protruding inside prevents saliva particles from being entrained. Foreign particles are rather separated by deflection, and they are collected in the lower part of the cup (U.S. Pat. No. 3,880,591). The mouthpiece, however, has no stop for inhalation or suction, so that an awkward blowing may both disturb the function of the measuring device and infect the tested person with germs which might escape therefrom.
Another prior art mouthpiece for the measuring head of a device for detecting alcohol in the breath is tubular and accommodates a check valve closing in the direction of inhalation. The mouthpiece is exchangeable. At one of its ends, the tubular mouthpiece is closed with a bottom. The breath outlet is provided below the check valve, in the side wall of the tube and at a location spaced from the bottom, so that a saliva collecting chamber is formed between the bottom and the outlet (German Pat. No. 28 20 916). The breath air leaves the mouthpiece laterally, wherefore no application is possible to conventional breath-alcohol measuring devices. Complicated tools are required for the manufacture which is therefore expensive.